Update statement taking long time

Question

Hi All,
The following query is taking too much time for update the 100000 records.
Please tell me how can this query time get reduced.
DECLARE
   CURSOR cur IS
     SELECT c.account_id FROM crm_statement_fulfilled_sid c;
BEGIN
   FOR i IN cur LOOP
     UPDATE crm_statement_fulfilled_sid a
        SET a.rewards_expired = (SELECT abs(nvl(SUM(t.VALUE), 0))
                                   FROM crm_reward_txns t
                                  WHERE txn_date BETWEEN
                                        (SELECT (decode(MAX(csf.procg_date) + 1,
                                                        NULL,
                                                        to_date('01-May-2011',
                                                                'DD-MM-YYYY'),
                                                        MAX(csf.procg_date) + 1))
                                           FROM crm_statement_fulfilled csf
                                          WHERE csf.procg_date < '01-aug-2012'
                                            AND account_id = i.account_id) /*points_start_date_in*/
                                    AND '01-aug-2012'
                                    AND reason = 'RE'
                                    AND t.account_id = i.account_id);
   END LOOP;
END;Any help?
Sid

Answer 1

Hoek wrote:
Second: you're doing row-by-row (= slow-by-slow) processing.
See if you can rewrite your code into a single SQL UPDATE statement that will process an entire SET at once.Well to be nitpicking. The op already does a single big update. He just does it again and again and again for each account id. Each time completely overwriting the values from the last account id.